Fifteen centuries of past annual fluvial inflows recorded in the varved sediments of Grand Lake, Labrador, Canada
Abstract
Northeastern Canada experiences significant interannual to multidecadal climate variability related to large-scale atmospheric and oceanic variability modes, such as the North Atlantic Oscillation (NAO) and the Atlantic Meridional Overturning Circulation (AMOC) making this region a key sector for the study of the North Atlantic hydro-climate system. Grand-Lake, Labrador, is a deep lacustrine basin that contains an exceptionally well-preserved annual laminations record spanning the interval 493 to 2016 CE (1523 years). The chronology of this varved sequence is established from two independent sources, i.e., high resolution images of thin sections at the scanning electron microscope, and high resolution µXRF profiles using the PeakCounter software. Radiocarbon dating is also used to validate the reliability of the varve chronology. The statistically significant correlation between varve thickness and the main tributary (the Naskaupi River) measured discharge provides the opportunity to develop the first hydrological reconstructions with annual resolution covering the last fifteen centuries at the western fringe of the Atlantic Ocean. Naskaupi River Q-mean reconstructed from the varve thickness series reveals high Q-mean conditions during the 10501225 CE period, that is corresponding to the Medieval Climate Anomaly, whereas the 15th19th centuries, matching the Little Ice Age, revealed low Q-mean conditions with significant multidecadal variability during the 15001750 interval. The reconstructed Q-mean shows a significant co-variability with two recent Atlantic Multidecadal Variability reconstructions (Lapointe et al., 2020, Wang et al., 2017) and with reconstructed summer Northern Hemisphere temperature based on tree rings (Wilson et al., 2016), suggesting that river discharge in Labrador was influenced by ocean-atmosphere interactions across North Atlantic and large-scale temperature variability during the last 1500 years.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMPP45E1139F